The role and uses of citric acid and precautions(1)

Citric acid is the number one organic acid and is easily soluble in water, making it a natural preservative and food additive. Depending on its water content, it can be divided into citric acid monohydrate and citric acid anhydrous. Due to its physical properties, chemical properties and derivatives, it is the most important organic acid widely used in the food, pharmaceutical and daily chemical industries. So, what are the specific roles and uses of citric acid?

I. The role of citric acid

Citric acid is mainly used as acidifier, solubiliser, buffer, antioxidant, deodoriser, flavour enhancer, gelling agent, colour mixing agent, etc. In addition, citric acid has the function of inhibiting bacteria, bacteria, bacteria and bacteria. In addition, citric acid is also used to inhibit bacteria, protect colour, improve flavour and promote the conversion of sucrose. Citric acid also has a chelating effect and can remove certain harmful metals. Citric acid can prevent oxidation caused by enzyme catalysis and metal catalysis, thus preventing discolouration and flavour change of frozen fruits.

1、Used in the food industry

Because citric acid has a mild and refreshing acidity, it is mainly used in food additives for carbonated beverages, fruit juice drinks, lactic acid drinks and other refreshing drinks and pickled products. The addition of citric acid to canned fruit can maintain or improve the flavour of the fruit in the collection, increase the acidity of certain fruits with low acidity when canned (lowering the pH), weaken the heat resistance of microorganisms and inhibit their growth, and prevent bacterial swelling and damage that often occurs in canned fruit with low acidity. The addition of citric acid as an acidulant in confectionery makes it easier to harmonise with fruit flavours. In gel foods such as jams and jellies, citric acid is effective in reducing the negative charge of pectin, thus allowing the hydrogen bonding between pectin molecules to gel. In the processing of canned vegetables, some vegetables are alkaline reaction, use citric acid as pH adjuster, not only can play a role in seasoning, but also can maintain its quality. Citric acid's chelating effect and pH-adjusting properties make it worthwhile to increase the performance of antioxidants in the processing of frozen foods, inhibit enzyme activity and prolong the shelf life of foods.

Citric acid monohydrate is mainly used as an acidic flavouring agent in cool drinks, fruit juices, jams, fruit candies and canned goods, and as an antioxidant in edible oils. It also improves the organoleptic properties of food, enhances appetite and promotes the digestion and absorption of calcium and phosphorus substances in the body.

Citric acid anhydrous is used in large quantities in solid drinks. Salts of citric acid such as calcium citrate and iron citrate are used as fortifying agents in certain foods where calcium and iron ions are required. Esters of citric acid such as triethyl citrate can be used as non-toxic plasticisers to manufacture plastic films for food packaging, acidulants and preservatives for the beverage and food industries.

2、Used in water treatment industry

Citric acid in water treatment has the role of sterilization, adjusting the pH value of water quality, the acidity of citric acid can change the pH value of cells and affect the normal metabolism of bacteria. Acidic high concentration of hydrogen ions can also change the biological activity of bacteria and directly damage the cells.